Control device and control method for a secondary battery

• US 9,906,060 B2
• Filed: 07/09/2014
• Issued: 02/27/2018
• Est. Priority Date: 09/06/2013
• Status: Expired due to Fees

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Ogihara, Wataru
• Primary Examiner(s): Pelton, Nathaniel
• Assistant Examiner(s): Torres Ruiz, Johali
• Application Number:
  US14/916,885
• Publication Number:
  US 20160218544A1
• Time in Patent Office: 1,329 Days
• Field of Search: 320134, 324429, 324433
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 58/15 Preventing overcharging
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/3828 using current integration
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/425 Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing printed circuits H05K1/00
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H01M 2010/4271 Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
• CPC Class Codes: H01M 2220/20 Batteries in motive systems, e.g. vehicle, ship, plane
• CPC Class Codes: H01M 4/505 of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
• CPC Class Codes: H01M 4/525 of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• CPC Class Codes: H02J 2310/48 for electric vehicles [EV] or hybrid vehicles [HEV]
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: H02J 7/007 Regulation of charging or discharging current or voltage
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries

Abstract

A control device for a secondary battery using positive electrode active material made of solid solution material, comprising: a voltage detecting unit configured to detect an actual open circuit voltage value; an SOC detecting unit configured to detect an actual state of charge value on a basis of the actual open circuit voltage value and/or an actual current value; a memory unit configured to store a voltage-SOC standard control curve which shows a relation between an open circuit voltage value and a state of charge value; a presumed voltage calculating unit configured to calculate a presumed voltage value on the basis of the actual state of charge value and the voltage-SOC standard control curve stored in the memory unit; a determining unit configured to determine sameness between the actual voltage value detected by the voltage detecting unit and the presumed voltage value calculated by the presumed voltage calculating unit.

Claims

1. A control device for a secondary battery using, as positive electrode material, positive electrode active material made of solid solution material, comprising:

a voltage detecting unit configured to detect an actual open circuit voltage value of the secondary battery;

a current detecting unit configured to detect an actual current value of the secondary battery;

an SOC detecting unit configured to detect an actual state of charge value on a basis of the actual current value of the secondary battery;

a memory unit configured to store a voltage-SOC standard control curve which shows a relation between an open circuit voltage value of the secondary battery and a state of charge value;

a presumed voltage calculating unit configured to calculate a presumed voltage value on the basis of the actual state of charge value detected by the SOC detecting unit and the voltage-SOC standard control curve stored in the memory unit;

a determining unit configured to determine a difference between the actual open circuit voltage value detected by the voltage detecting unit and the presumed voltage value calculated by the presumed voltage calculating unit; and

a control unit configured to at least perform a discharge process so as to make the difference between the actual open circuit voltage value and the presumed voltage value smaller before a next charge process when the difference is determined higher than a predetermined range by the determining unit.

2. The control device as set forth in claim 1, wherein the determining unit determines the difference on the basis of whether a difference of the actual open circuit voltage value and the presumed voltage value is within a predetermined range or not.

3. The control device as set forth in claim 2, wherein the control unit:

controls the secondary battery by using the actual open circuit voltage value when the determining unit determines that the difference of the actual open circuit voltage value and the presumed voltage value is within the predetermined range; and

performs a discharge process so as to make the difference smaller before a next charge process when the determining unit determines that the difference of the actual open circuit voltage value and the presumed voltage value is not within the predetermined range.

4. The control device as set forth in claim 3, wherein the control unit sets an upper limit voltage value of the next charge process for a voltage value lower than a previous upper limit voltage value when the determining unit determines that the difference of the actual open circuit voltage value and the presumed voltage value after performing the discharge process is not within the predetermined range.

5. The control device as set forth in claim 3, wherein the control unit performs the discharge process in a case of performing a predetermined number of a charge process, regardless of a determined result by the determining unit.

6. The control device as set forth in claim 3, wherein the control unit performs to supply electric power generated by the discharge process to a stationary battery which is electrically connected via an external control device.

7. The control device as set forth in claim 3, wherein the control unit performs to supply electric power generated by the discharge process to another secondary battery which is mounted on a vehicle.

8. The control device as set forth in claim 1, wherein the control unit performs the discharge process at a discharge rate of 1 coulomb or less, the discharge rate of 1 coulomb being a current value a when a secondary battery having a nominal capacity of a is discharged by 1 hour.

9. The control device as set forth in claim 1, wherein the control unit performs a number of the discharge processes.

10. The control device as set forth in claim 9, wherein the control unit stepwise decreases a discharge rate in the discharge processes.

11. The control device as set forth in claim 1, wherein the solid solution material is a transition metal oxide containing solid solution lithium having a compositional formula of Li_1.5[Ni_aCo_bMn_c[Li]_d]O₃, in the compositional formula, Li denotes lithium, Ni denotes nickel, Co denotes cobalt, Mn denotes manganese and 0 denotes oxygen, a, b, c and d satisfy relationships:

0<

a<

1.4;

0≦

b<

1.4;

0<

c<

1.4;

0.1<

d≦

0.4;

a+b+c+d=1.5; and

1.1≦

a+b+c<

1.4,

the transition metal oxide containing solid solution lithium includes a layered structure region and a region changed to a spinel structure by being subjected to charge or charge/discharge in a predetermined electrical potential range,

a spinel structure change ratio of the transition metal oxide containing solid solution lithium is 0.25 or more to less than 1.0 when a ratio of an entire change from Li₂MnO₃ with the layered structure to LiMn₂O₄ with the spinel structure is defined to be 1.

12. A control method for a secondary battery using, as positive electrode material, positive electrode active material made of solid solution material, comprising:

detecting an actual open circuit voltage value of the secondary battery;

detecting an actual current value of the secondary battery;

detecting an actual state of charge value on a basis of the actual current value of the secondary battery;

storing a voltage-SOC standard control curve which shows a relation between an open circuit voltage value of the secondary battery and a state of charge value;

calculating a presumed voltage value on the basis of the actual state of charge value detected by an SOC detecting unit and the voltage-SOC standard control curve stored by the storing step;

determining a difference between the actual open circuit voltage value detected by the actual open circuit voltage detecting step and the presumed voltage value calculated by the presumed voltage calculating step; and

at least performing a discharge process so as to make the difference between the actual open circuit voltage value and the presumed voltage value smaller before a next charge process when the difference is determined higher than a predetermined range.